One addition to the thread. I bought a set of 700 ivory horsehead chips in 1980 from a woman in Syracuse, age 86, whose great uncle ran an illegal club in Saratoga in the mid to late 1800's. The box contained the original shipping label from a NYC firm and was dated 1856. So ivory chips were used by casinos prior to 1860. For personal reasons (I was in a divorce action) I could not own the chips and brokered them to Dale Seymour. I think many of us now have a set of the four chips which are either ID-CG or CH, off hand I can't recall.